What are the recommended doses for ibuprofen (Nonsteroidal Anti-Inflammatory Drug) and acetaminophen (paracetamol)?

Recommended Doses for Ibuprofen and Acetaminophen

For adults with acute pain, acetaminophen should be dosed at 1000 mg every 4-6 hours (maximum 4 grams daily), and ibuprofen at 400 mg every 6-8 hours (maximum 3200 mg daily), with the combination of both drugs providing superior analgesia to either agent alone. 1

Acetaminophen (Paracetamol) Dosing

Standard Adult Dosing

• Oral/IV: 1000 mg every 4-6 hours is the recommended first-line dose for mild to moderate pain 1
• Maximum daily dose: 4000 mg/day 1
• Loading dose (IV): 15-20 mg/kg can be used initially 1
• Maintenance (IV): 10-15 mg/kg every 6-8 hours 1

Pediatric Dosing

• Oral: 10-15 mg/kg every 6 hours (maximum daily dose: 60 mg/kg) 1
• IV loading dose: 15-20 mg/kg 1
• Rectal loading: 20-40 mg/kg (15 mg/kg if <10 kg) as single dose; higher rectal doses compensate for poor bioavailability 1

Critical Safety Considerations

• Hepatotoxicity risk: Exceeding the maximum daily dose can cause severe liver damage, requiring cautious use in patients with liver failure 1
• Frail patients: Exercise particular caution in elderly patients and those with coexisting liver disease, as increased alanine aminotransferase levels have been observed even at therapeutic doses 1

Ibuprofen Dosing

Standard Adult Dosing

• Oral: 400 mg every 6-8 hours is the optimal dose for most acute pain situations 1, 2
• Alternative dosing: 400 mg every 4-6 hours for cancer-related pain 2
• Maximum daily dose: 3200 mg/day 2
• IV (perioperative): 800 mg every 6 hours has been shown safe and effective in emergency abdominal surgery 1

Pediatric Dosing

• Standard: 10 mg/kg every 8 hours (oral, rectal, or IV) 1, 2

Dose-Response Considerations

• Minimal effective dose: 200 mg is the smallest clinically useful single dose 3
• Optimal dose: 400 mg provides the best balance of efficacy and safety; doses above 400 mg offer limited additional analgesic benefit 3, 4
• Duration of action: 400 mg provides at least 6 hours of analgesia compared to 4-6 hours for 200 mg 3

Critical Safety Monitoring

• High-risk patients (>60 years, history of peptic ulcer, significant alcohol use) require monitoring for gastrointestinal complications 2
• Renal monitoring: Stop ibuprofen if urea or creatinine doubles or if hypertension develops or worsens 2
• Cardiovascular caution: Patients with cardiovascular disease history should be treated cautiously 2
• GI bleeding: Discontinue immediately if gastrointestinal bleeding or peptic ulcer occurs 2

Combination Therapy: Superior Efficacy

Evidence for Combined Use

The combination of ibuprofen 400 mg + acetaminophen 1000 mg provides significantly better pain relief than either drug alone, with 73% of patients achieving at least 50% pain relief versus 52% with ibuprofen alone. 5

Practical Combination Dosing

• Standard combination: Ibuprofen 400 mg + acetaminophen 1000 mg every 6 hours 5
• Lower-dose combination: Ibuprofen 200 mg + acetaminophen 500 mg every 6 hours (also effective but less potent) 5
• Postoperative setting: Ibuprofen 600 mg every 6 hours + acetaminophen 500 mg every 6 hours provides adequate pain control 1

Advantages of Combination Therapy

• Longer duration: Median time to rescue medication is 8.3 hours with the 400/1000 mg combination versus 1.7 hours with placebo 5
• Reduced rescue medication need: Only 25% of patients require additional analgesia with the combination versus 48% with ibuprofen alone 5
• Opioid-sparing effect: Combination therapy reduces opioid consumption and related complications 1
• Better tolerability: Lower adverse event rates (29%) compared to placebo (48%) 5

Clinical Context and Special Situations

Cancer Pain

• Acetaminophen 1000 mg every 4-6 hours is recommended as first-line for mild to moderate cancer pain 1
• Ibuprofen 400 mg every 4-6 hours (maximum 3200 mg/day) is particularly effective for inflammatory and bone pain 1, 2

Postoperative Pain

• Multimodal approach preferred: Both drugs should be used together as part of enhanced recovery protocols 1
• IV acetaminophen: May be superior to IV tramadol in laparoscopic procedures 1
• Preemptive analgesia: Acetaminophen 1000 mg given before surgery reduces opioid requirements and length of stay 1

Important Drug Interactions

• NSAIDs with methotrexate: Absolutely contraindicated 1
• NSAIDs with nephrotoxic chemotherapy: Use with extreme caution, particularly with cisplatin 1
• Aspirin interference: Ibuprofen can interfere with aspirin's cardioprotective effects; timing of administration matters 6
• Never combine two NSAIDs: Do not prescribe ibuprofen with other NSAIDs like ketorolac due to dramatically increased risk of GI bleeding, acute kidney injury, and cardiovascular events 6

Comparative Efficacy

Ibuprofen 400 mg is superior to acetaminophen 1000 mg for acute pain, with a risk ratio of 1.47 for achieving 50% pain relief and 1.50 for avoiding rescue medication. 7, 8